The film opened in Nevada in 1957, at a restricted secret weapons testing site in the desert that was infiltrated by Soviets, led by Russian Colonel Dovchenko (Igor Jijikine) and villainous, jet-black Cleopatra-banged, psychic research scientist and Russian agent Dr. Irina Spalko (Cate Blanchett), disguised as US military. Held captive were archaeologist Dr. Henry "Indiana" Jones (Harrison Ford) and his long-time compatriot partner George "Mac" McHale (Ray Winstone). In the military warehouse (the one that the U.S. Government had hidden the Ark of the Covenant at the end of Raiders of the Lost Ark (1981)) at the testing site, the Russians sought a rectangular crate with "mummified remains" (an extra-terrestrial skeletal life form that had crashed in Roswell, New Mexico in 1947) that Jones had examined ten years earlier. He led them to a highly-magnetized steel crate where the alien corpse was found, and then held off the Russians with a gun, but was double-crossed by "Mac" with dubious loyalties who was being paid by the enemy.

In the confusion, however, Indy escaped during an action-packed chase/pursuit sequence involving his bullwhip atop the crates. He found himself seated on a rocket engine that propelled him into the desert, where he ended up in Doomtown - a nuclear weapons test town of homes filled with plastic dummies. To avoid the effects of a nuclear explosion detonated by the military, he hid in a lead-lined refrigerator and survived. He was found by the FBI and debriefed, regarded suspiciously because of his association with McHale. Indy returned to his teaching position as Professor of Archaeology at Marshall College, where academic friend/colleague Dean Charles Stanforth (Jim Broadbent) - who had resigned - gave him an "indefinite leave of absence" rather than outright firing him, because of the continuing investigation and suspicions that he was a Communist. [It was learned that both Dr. Marcus Brody and his father Henry Jones, Sr. were deceased.] Dr. Jones prepared to leave, and possibly take a train to New York and a flight to London during his absence.

As the train pulled away from the station, he was confronted by 'greaser' "Mutt" Williams (Shia LaBeouf), who told him that his old colleague Dr. Harold Oxley (John Hurt) from 20 years earlier was going to be killed. Dr. Jones exited the train and they went to a 1950s style diner to discuss Oxley's work, and Mutt's relationship to him (Oxley was revealed as Mutt's surrogate father: "My dad died in the war. Ox kind of helped my mom raise me"). Six months earlier, Mutt's mother had received a letter from Oxley in Peru, where he was working and had found some type of "crystal skull." He considered the skull real and was off with it to a place called Akator (Indy described the legend surrounding the skull. Akator was "a mythical lost city in the Amazon. Conquistadors called it El Dorado. Supposedly the Ugha tribe were chosen by the gods 7,000 years ago to build a giant city out of solid gold. It had aqueducts and paved roads and technology that wouldn't be seen again for 5,000 years. Francisco de Orellana disappeared into the Amazon looking for it in 1546...The legend says that a crystal skull was stolen from Akator in the 15th or 16th century, and that whoever returns the skull to the city temple will be given control over its power").

Mutt went on to say that his mother went to Peru to find Ox, and discovered that he had been kidnapped - and she was also kidnapped. They were threatened with being killed if they didn't reveal the location of the skull, and his mother, named Mary Williams, told Mutt that Indy could probably help: "If anybody could find the skull, it's you." She had escaped (or was deliberately let go), however, and sent Mutt the most recent letter from Oxley. Indy took the letter to read it, and then was abruptly confronted by two KGB agents trailing him. A fight in the diner afforded Indy and Mutt an opportunity to escape, although the Soviets chased them. They rode together on Mutt's motorcycle through the streets of the college campus (where anti-Communist protests were occurring - "Better Dead than Red"), and into the school's library.

When Indy was able to further examine Oxley's letter, he discovered the word "Koihoma" - a word from a "dead" or extinct Latin American language, and determined: "It's a riddle...Follow the lines in the earth only gods can read which lead to Orellana's cradle guarded by the living dead. He's talking about the Nazca Lines... Geoglyphs. Giant ancient drawings carved into the desert floor in Peru...From the sky, only the gods can read them because only gods live up there. Oxley's telling us the skull is in Nazca, Peru." The two flew to Peru from New York, where they learned that Oxley had been locked up in the local sanitarium for being "obsessed, deranged." However, they also found that Oxley had been taken away by men with guns a few weeks earlier, although he had drawn pictures on the walls of his cell. Indy surmised that Orellana wasn't born in Peru but in Spain, and disappeared with six others when searching for New World gold.

In Oxley's cell, they deciphered the drawings of a skull with an elongated cranium, and the word Ruckkehr (meaning "Return") in different languages. Indy noted that the word 'cradle' literally meant 'final resting place.' The clues led them to a local cemetery, where they were attacked by locals wearing skeleton masks and firing poisonous darts through blow tubes. Within one of the cemetery's deep caves, they located the grave of missing conquistador Francisco de Orellana and six others - and here, they found the "unbelievable" crystal skull hidden by Oxley - "a single piece of seamless quartz" with magnetic properties. Mutt surmised: "Maybe the Nazca Indians thought this was their god. You think this is the one from Akator?" Indy wondered: "Maybe the Spaniards found this skull along with all this other loot. They were headed for their ships along the shore. Maybe the Indians caught up with them, or they got to squabbling amongst themselves over their prize, kill each other off. The Indians wrap them up and bury them. A couple of hundred years later, Oxley shows up here, finds the skull. Takes it away, maybe to Akator. But then he returns it here...He put it back where he found it. Why?"

As the two left the cemetery, they were confronted by "Mac" and Colonel Dovchenko at gunpoint, and were flown into the interior jungles where the Russians were camped on the Amazon River. Dr. Irina Spalko appeared, expressing her interest in the skull's ultimate global domination powers for use in warfare, after it was returned to Akator, although Indy doubted that it was only a legend: "This next level of weapon is ours to have, yours to fear...A mind weapon. A new frontier of psychic warfare. That was Stalin's dream...(The skull) was not made by human hands...The body we found in New Mexico was not the first. We'd already dissected two others from similar crash sites in Soviet Union...The legends about Akator are all true. Early men could not have conceived it, much less built it. It was a city of supreme beings with technologies and paranormal abilities...The New Mexico specimen gave us hope. Unlike the others we'd found, its skeleton was pure crystal. A distant cousin, perhaps. Maybe they, too, were sent to find Akator. Perhaps we're all searching for the same thing. There is no other explanation...The skull was stolen from Akator in the 15th century. Whoever returns it to the city temple will gain control over its powers."

The Russians had taken Oxley prisoner as well, although he could only mutter incomprehensible words, due to the effects of the crystal skull: "He is the divining rod that will lead us to Akator." They needed Indy as someone to interpret Oxley for them and lead them to Akator. "The skull's crystal stimulates an undeveloped part of the human brain, opening a psychic channel. Oxley lost control of his mind by staring too long into its eyes. We believe you can get through to him after you have done the same." They forced Indy to stare at the skull, believing that at Akator, "whoever finds them (skulls) will control the greatest natural force the world has ever known. Power over the mind of man. Imagine, to peer across the world and know the enemy's secrets. To place our thoughts into the minds of your leaders. Make your teachers teach the true version of history, your soldiers attack on our command. We'll be everywhere at once, more powerful than a whisper, invading your dreams, thinking your thoughts for you while you sleep...We will turn you into us. And the best part? You won't even know it's happening."

Indy was completely shocked when the Russians revealed Mutt's mother - Indiana's old girlfriend/lover Marion Ravenwood (Karen Allen). He understood how Ox was drawing ideograms to communicate - wavy lines (water), closed eyes (sleep), sun in sky (time duration), now = until, horizon (big or great) and snake (the Amazon). Indy interpreted: "The water sleeps until the great snake" - "These aren't just drawings, they're directions!" With a map, he guessed that they would follow the curve of the Sono River down to where it met the Amazon to the SE, an unexplored part of the jungle rainforest. Mutt, Indiana, Marion, and Oxley escaped into the jungle, where they encountered quicksand, and as Marion and Indy sank, he learned that Mutt's real-name was Henry Jones III - Mutt was his own biological son!

They were recaptured when Oxley went to get "help," although they were able to escape from a transport truck in the jungle, followed by an exciting and spectacular chase sequence, including a sword fight atop side-by-side moving vehicles between Mutt and Dr. Spalko, and a cliff-edge challenge. During the fierce pursuit scene as everyone struggled to get possession of the crystal skull in a burlap bag, Mac claimed that he was a double-agent, actually working for the CIA. After an attack by wild monkeys, Colonel Dovchenko met his death in a mound of giant siafu ants. To evade capture by the Russians, the five of them successfully launched their amphibious vehicle over a cliffside into a raging river, but faced three gigantic rapids drops in the water ("Three times it drops!"). Surviving the river's triple falls, they entered a cave through another misty waterfall and studied cave paintings (one showed thirteen alien beings with elongated skulls in a circle). Native Ugha warriors who defended the temple attacked them as they approached the pyramid-shaped temple of Akator (or the legendary city of El Dorado) in the Amazonian rainforest - the crystal skull in Oxley's hands kept the natives back as they entered. Mac was revealed to still be traitorous as he left a trail of red-blinking homing devices for the Soviets to follow.

The five had to decipher one last clue: "To lay their just hands on that Golden Key that ope's the Palace of Eternity." Indy guessed that the obelisk was "the key" - removing its headstones caused sand to flow out of it, triggering the temple's chamber entrance to open. A disappearing descending staircase was another trap that they hurriedly avoided. The five entered another outer-chamber filled with artifacts from every era of early history ("the mother lode"), and then approached the inner chamber after opening its puzzle-like doorway entrance. They gazed in awe upon thirteen alien crystal skeletons, one missing a skull, seated on thrones in a circle. Mac revealed his complicity ("triple agent") with the Soviets as he held his gun pointed at them. When Dr. Spalko arrived, she marveled: "Still waiting for the return of the one who was lost. They are a hive mind. One being physically separate, but with a collective consciousness. More powerful together than they could ever be apart. Imagine what they could tell us." She took the crystal skull from Oxley's arms and placed it onto the one headless skeleton.

The group of alien beings began communicating through Oxley in an ancient Mayan dialect. Indy interpreted that for restoring the alien's skull, "it wants to give us a gift, a big gift." Spalko stepped forward and volunteered to the alien: "Tell me everything you know. I want to know everything. I want to know." Indy feared: "I've got a bad feeling about this." She was granted what she requested - as the temple began to crumble around them. Oxley recovered his sanity and exclaimed that the aliens were "inter-dimensional beings," when a spinning temporal portal or pathway to another supernatural dimension opened above them. Indy and the others fled from the chamber, but all of the Soviet agents were sucked upward along with debris, as Dr. Spalko kept urging from the middle of the room: "I want to know. I want to know. Tell me. I'm ready. I want to know. I can see!" As the aliens' collective knowledge in their crystal skulls was transferred into her mind, her eyes and brain ignited and exploded, and her body disintegrated into pieces as it was absorbed into the portal. Mac couldn't be saved by Indy as he was preoccupied by greed and died in the rubble.

In the spectacular finale, the remaining group of four escaped from the crumbling, flooding valley temple as a flying saucer emerged from the spinning debris and disappeared. All traces of the temple vanished as Indy asked: "Where did they go? Space?" Oxley replied: "Not into space. Into the space between spaces." Indy summed up: "The Ugha word for 'gold' translates as 'treasure.' But their treasure wasn't gold. It was knowledge. Knowledge was their treasure." In the short epilogue, Indy was made Associate Dean of Marshall College, and the long-awaited marriage between Indy and Marion was finally consummated.

Great Scene(s): Indy's escape from a nuclear explosion by hiding in a lead-lined refrigerator, the swordfight atop two moving vehicles in the jungle, a skin-crawling attack by millions of giant killer siafu ants, the sight of 13 alien ("inter-dimensional beings") crystal skeletons seated in a circle on thrones in an ancient underground chamber, the demise of Spalko when her brain exploded from the overwhelming 'gift' of knowledge, and a spectacular finale in which the crumbling valley temple was sucked into a portal and a flying saucer emerged.

Film Notables (Awards, Facts, etc.)

With 64-year old Harrison Ford reprising his role 19 years after the last installment of the series-franchise.

With a production budget of approximately $185 million, the film grossed $317 million (domestic) and $786 million (worldwide).

No Academy Award nominations.

The main religious artifact or icon: The Mitchell-Hedges crystalline skull, revealed to be the skull of an ancient inter-dimensional alien - possibly an ancient alien "supercomputer" providing ultimate knowledge.